Electric lamp



Sept. V20 1932 F. MEYER ET AL 1,877,932

ELECTRIC LAMP Filed Deo. 19, 1927 l Z' J3 37 f 4d ATTORNEY .posed of the anode drop,

,present employed Patented Sept. 2 0, 1932 UNITED STATES PATENT OFFICE EEiEDEIcE MEYER, or EEELINHALENSEE EDMUND GEEMEE, or s'rocEHoLM, SWEDEN, Assrcnons, BY MEsNE INafApoEroEA'rIoN or DELAWARE GERMANY, AND ASSIGNMENTS, T0 ELECTRONS,

HANS-JOACHIM SPANNEE, or BERLIN,

ELECTRIC LAMP i Application led December 19, 1927, Serial No.

Our invention refers to electric lamps, more especially of the kind employed insign-lighting in which electrical glow discharges are caused to pass across a bod of gas under reduced pressure. It is'an o ject of our invention to provide a lamp of the kind aforesaid which is better adapted Jfor practical use than similar lamps hitherto known.

The glow lamps such as nowadays in use for advertisement illumination and similar purposes are of a rather complicated construction. The glass bulbs or tubes filled with rare or other gas, for instance argon or neon and provided with suitable electrodes are inserted in a circuit having a high voltage whereby a permanent glow current is generated between the electrodes and across the gas filling the tube.- In lamps of this kind which are operatedl with alternating current, ordinary cold elect-rodes having very little electronic-activity are employed. These tubes require high voltages in proportion to their length, and with alternating current such voltages can easily be attained. .The drop'of voltage in tubes of this kind is comthe cathode drop and the ldrop in the path of discharge. The anode drop as a rule .amounts to a few volts only, the drop of voltage in the path oi discharge amounts to 1-20 volts per centimetre of the length of path, according to the diameter of the tube. In contradistinction thereto the drop at thev cathode is-considerable and ranges between 120 and 400 volts, de-

I pending on the nature of the gas in the tube.

An object of our invention is to produce a luminous glow discharge device for advertising purposes which device has a low starting potential and which is much more highly eficient in light production than the tubes at for such use. Further objects of our invention will appear more fully hereinafter .as -the description of the appa- `oifthe rare or lnert gases either singly or as mixtures depending upon ratus is developed.

Our invention consists substantially in the construction, combination and arrangement of parts associated in our improved glowv lamp and the electrical system actuating the same as will be more fully set forth herein- 241,035,A and' in Germany December 10, 1928.

after and as shown by the accompanying drawing and nally pointed out in the appended claims. l Reference is to be had to the accompanylng drawing forming apart of this specification in which like reference characters indicate corresponding parts throughout the several views and in which Fig. 1 is a diagrammatic illustration of the simplest form of our improved lamp and the electrical system for operating the same.

, Fig. 2 is an improvement over the device shown in Fig. 1 as will be described in detail hereinafter, and

Fig. 8 is a modification thereof.

- Referring particularly to Fig. 1, 1 designates an envelope impervious to gases and having therein a plurality of electrode stems 2. These stems and the portion of the envelope in close proximity thereto consist of the usual lead glass to which the portion of the envelope 1 which is to be used for its luminous eects is sealed by means of splicing glass 3. f

This portion of theenvelope 1 may be of ray pervious glass, of uranium glass or didynium glass; surrounded by a colored liquid as shown at l1;'having a luminous coating'thereon as shown at 5; having a section 6 sealed therein of etched luminous glass; or containing suspended therein luminous designs as indicated at 7.

Through the stems 2 are sealed the usual type .of lead-in wires 8, 9, 10 and 11,-which carry lelectrodes 12" and 13 maintained Iin fixed relation to the stems 2 by meansv of supports 14,15. l c The electrodes 12 and 13 are of the ilamentary type and may consist of' molybdenum, tungsten, or thorium, either singly or alloyed together; may be of the usual Wehnelt type of cathode with various electronic emissive coatings thereon.

The envelope 1 contains a small quantity the particular luminous effect desired.`

The supply system 'for our improved glow lamp is as follows: 20 designates the source of alternating current across which is conand 13 follow the potential of the terminals of the source of power 2O so that each alternately acts as an anode and as a cathode with re ect to the other electrode.

hen current flow is maintained through the tube the ionic bombardment of the luminous coating within the tube, ofthe luminous designs within the tube or of the luminous glass itself will produce a visible glow which may be utilized in advertising signs and the like. The passage of current through the gas within the tube itself will produce a glow `within the tube of color dependent upon the gas which glow may be given various luminary effects by means of the colored liquid surrounding the glass or the etched luminous A portions of the envelope. It is to be understoodthat these features are to be considered as -applicable to the devices shown and described with 'reference to Figures 2 and 3 although specific mention of` the various luminary effects is not specifically stated.

Referring to Fig. 2 I have shown a glow discharge tube and a supply system in which like reference characters designate like parts as those described with reference to Fig. 1. In this particular case however, we have provided a 'plurality of auxiliary electrodes 28 and 29 supported upon the stems 2 by means of metallic supporting members 30, 31. These auxiliary electrodes are maintained at the potential of their corresponding main electrodes by means of electrical connections shown 'at 32. Each of these auxiliary electrodes is positioned directly in the path of current flow between the electrodes 12 and 13. In the operation of this device it will be seen that since the auxiliary electrodes 28 and 29 are always at the same potential as the electrodes l2 and 13 the ionic stream strikes ,these electrodes with the result that the electrodes 12 and 13 are protected from deterioration by ionic bombardment. I

In Fig. 3 we have shown means whereby a tube may be started and operated at low voltage by producing a low drop of voltage at the cathode at each half cycle of alternating current ow through said tube. In this case wearrange at the side of the glow electrodes 12 and 13 auxiliary electrodes 35 and 36 in closely spaced relationthereto.

We havefsh'own the lead-in lwires 8, 9and electrodes 12 and 10, 11 shorted, so that the 'in shop window advertising 2 without departing from'the spirit of our invention.

The connections for the simple direct connection from the source of alternating current power 20 to the electrodesi'12, 13, 35 and 36'are as followszf'lerminal 37 of the source 20 is connected to the electrode 12 through the coil 38 of a circuit breaker 40 and to the electrode 36 through the armature and contacts 41 of a circuit breaker 42 and resistance 43. Terminal 44 is connected to the electrode 13 through the coil 45 of the circuit breaker 42 and to the electrode 35 through the armature and contacts 46 of the circuit breaker 40 and a resistance 47.

The resistances 43 and 47 are of such a value that once the tube is operating the current flow between'the electrodes 35 and 12 and the electrodes 13 and 36 will be much smaller than the current flow between the electrodes 12 and 13.

The operation ofthis arrangement is as follows: the circuit of the ytube being closed' auxiliary ignition being cutout automatithe glow cathodes 12 and 13, thev cally by the operation of the armatures 41 and 46 of the circuit breakers 42 and 40.

From the foregoing description it will be seen that we have produced a glow discharge tube and an operating system therefor which when operating upon alternating current will produce in consequence ofthe extremely low drop of voltage at Vthe cathodes a very steady light and which will have a very long life, inasmuch as in view of the low drop of voltage almost no disintegration of the electrodes will take place. A tube of this kind at the same time solves a further problem, viz: the provision of a low voltage alternating current lamp for use at places where high voltage lamps are too dangerous for use, such as and the like. Moreover, numerous tubes of this kind can be connected to any normal alternating current system without requiring any costly high voltage apparatus. l A

It will be understood that the foregoing description` and accompanying drawing comprehend only the general and preferred embodiments of our invention and that minor detail changes in the construction and general arrangement of parts may be made within the scope of the appended claims without sacrificing any of the advantages of our invention.

Having thus described our invention what we claim is:

1.- In a glow lamp system including an envelope having a gas therein, and a plurality of incandescible electrodes spaced apart therein, the combination of a transformer having a primary and a plurality of secondaries corresponding in number to said electrodes, connections between each secondary and its corresponding electrode and means for maintaining the mid-point of each secondary at a predetermined potential relative to the terminals of said primary wherebyeach of said incandescible electrodes acts alternately as a cathode and as an anode when said primary'is energized by alternating current.

2. In a glow lamp System including an envelope having a gas therein, and a plurality of incandescible electrodes spaced apart therein, the combination of a transformer having a primary and a plurality of secondaries corresponding in number to said electrodes, connections between each secondary and its corresponding electrode, means for maintaining the midpoint of each secondary at a' redetermined potential relative to the terminals of said primary whereby each of said incandescible electrodes acts alternatively s a cathode and as an 4anode when said primary is energized by alternating current, and an auxiliary conductive metallic shield connected to one ormore of said electrodes adjacent thereto and extending in the direction of the discharge path wherebythe siid shield will operate as an auxiliary catho e. A

' In testimony whereof we aix our signa.-

tures.

FRIEDRICH MEYER.

HANS-JOACHIM SPANNER. EDMUND GERMER. 

